Research On Dynamic Subcarrier Allocation Schemes For OFDMA System

Orthogonal frequency division multiple access (OFDMA) is one of the common used multiple access techniques. By integrating dynamic resource allocation, OFDMA is able to make full use of wireless spectrum, and improve system performance greatly.By researching the existed resource allocation algorithms for OFDMA system, especially for the subcarrier allocation algorithms, two new dynamic subcarrier allocation schemes were proposed in this paper, and simulation results were given by using MATLAB. The optimization objective of these two schemes is to minimize the total transmit power while guaranteeing users' data rate and target BER at the receiver.The first proposed scheme uses the idea of iteration. At each iteration, one subcarrier is allocated to a special user who need this subcarrier most, that is to say, allocate the subcarrier to the user whose transmit power will be increased most if it cannot get this subcarrier.The second proposed scheme is based on unified priority. The main idea of this scheme is to determine the allocation order for all subcarriers at a time according to users' channel gain and average channel gain, and the allocation priority for the subcarriers is fair and effective. Once determining the allocation priority, the allocation will be easy, just to allocate one by one in order.Simulation results show that these two proposed schemes have better performance and lower computational complexity compared with traditional dynamic subcarrier allocation algorithms.